1. Technical Field
This invention generally relates to querying a database in a computer database system, and more specifically relates to a using a partially built index to access a database.
2. Background Art
Databases are computerized information storage and retrieval systems. A database system is structured to accept commands to store, retrieve and delete data using, for example, high-level query languages such as the Structured Query Language (SQL). The term “query” denominates a set of commands for retrieving data from a stored database. The query language requires the return of a particular data set in response to a particular query. The database manager may use an index to find the requested data by the query. A large database requires many large indexes that must be maintained to efficiently access the database.
When these large indexes are being created or rebuilt, the database manager determines the index is not complete. When an invalid state occurs, the database manager marks an incomplete or outdated index as invalid and then the database manager requests a server job to rebuild the index. This is problematic because when the index is marked “invalid”, the index can not be used by any query and the index may take a long time to rebuild, hours, or perhaps days.